Artificial heart cycling system



1967 v. w. sous 3,337,878

ARTIFICIAL HEART CYQLING SYSTEM Filed Oct. 15, 1964 26 23 32 3| 27 r I i" KN 29 2 FIG! l5 J I 30 I9 I7 @20 34 i ra I. ZENER STABILIZED POWER SUPPLY OUTPUT VOLTAGE x I v s; q l W F g0. I i j jL R3 AAAA UNIJUNCTION RELAXATION OSCILLATOR MONOSTABLE MULTIVIBRATOR I N VEN TOR.

VICTOR W BOLIE BY ATT'YS United States Patent 3,337,878 ARTIFICIAL HEART CYCLING SYSTEM Victor W. Bolie, Tustin, Calif., assignor to Iowa State University Research Foundation, Inc., Ames, Iowa, a corporation of Iowa Filed Oct. 15, 1964, Ser. No. 404,028 4 Claims. (Cl. 3-1) ABSTRACT OF THE DISCLOSURE An artificial heart pump apparatus which is not subject to valve-stiction catastrophe. The apparatus includes a Background'of the invention This invention relates to artificial heart apparatus and more particularly to a heart pump including novel means for preventing valve-stiction catastrophe through pneumatic isolation of the high pressure source during systole.

Investigations leading toward the design of a chronic artificial heart have the important by-products of (a) developing a valuable tool for studying the physiological and pharmacological responses of the vascular system with a heart of rigidly controlled characteristics, (b) contributing to the growing knowledge of the hemodynamic characteristics of the mammalian heart through study and careful extrapolation of the properties of the simulation model, and (c) advancing the state of the art of perfecting materials and techniques for implanting and maintaining function internal prosthetic devices.

For some time, the workers in the art have supported the concept of transmitting the necessary hydraulic power to the blood by pneumatic methods. The advantages of using pneumatic methods to convert (but not transmit over long distances) primary power into mechanical power originate in large part from the energy storage density aiforded by compressed gases. The energy storage densities of electric and magnetic fields rarely exceed 5000 joules per cubic meter with practical capacitors and inductors, whereas 10,000 times this amount can be stored easily in compressed air at 100 atmosphere-s. One of the main problems heretofore encountered in heart massage study was that the ordinary pneumatic method of metering compressed air into the housing enclosing the collapsible ventricle produced rapid catastrophic results if the valve stuck during systole. It is therefore an object of the invention to provide a pneumatic method for actuating a heart pump which overcomes this difliculty.

Another object is to provide a heart pumping system embodying a multiport valve and a variable volume storage tank for supplying the required air pressure pulses in short, controllable, repetitive bursts with almost ideally sharp leading edges.

Still another object is to provide an artificial heart apparatus which can be driven at variable rates and duty cycles and still provide a stroke-limiting function.

Other objects and advantages of the invention may be seen in the details of construction and operation set down in this specification.

The invention is explained in conjunction with the accompanying drawing, in which-- Patented Aug. 29, 1967 FIG. 1 is a schematic representation of the mechanical portion of the artificial heart apparatus, and

FIG. 2 is a wiring diagram showing the electrical com ponents of the apparatus.

In the illustration given and with reference first to FIG. 1 the numeral 10 designates a schematic representation of an artificial heart pump which may take the form of the chamber providing vessel and collapsible bags shown in detail in my copending application Ser. No. 261,426, filed Feb. 27, 1963, now Patent No. 3,182,335, issued May 11, 1965. The pump 10 is coupled to a four Way valve generally designated 11 by means of a conduit 12. The valve advantageously may be a five port solenoiddriven spring-return four-way valve such as is available commercially as Modernair No. BV 40602-B.

As seen in FIG. 1 the port 13 is coupled to the pump 10 by means of the conduit 12. Further as seen in FIG. 1, the numeral 14 designates a spool movably positioned within the valve 11 and in the position shown has an internal passage 15 coupling the port 13 with a suction port 16. The suction port 16 is communicated with a source of suction 17 by means of a interposed in the conduit 18 is a suction adjustment device or regulator 19 and a meter 20.

Also when the spool 14 is in the municating ports 13 and 16), a second way or passage 21 in the spool connects ports 22 and 23. The port 22 is connected by means of a conduit 24 to a source of compressible pressure fluid 25 and also it includes a pressure regulator 26 and meter 27. Still further, an adjustable restriction 28 is interposed in the conduit 24 and this may take the form of a screw driver-adjustable fiow control valve as marketed under the designation Schrader No. 3250A.

The port 23 is coupled by means of conduit 29 to an adjustably expansible or variable volume reservoir generally designated 30. The reservoir 30 is seen in the illustrated embodiment to include a cylinder 31 equipped with a piston 32 slidably positioned therein. The piston is equipped with a crank fitting 32a.

In the alternative position of the spool 14, a way or passage 33 (shown in dotted line) couples ports 13 and 23. The bottom left hand port is closed by a plug 34.

In the operation of the mechanical system just described, the positioning of the spool 14 as shown couples the compressible pressure fluid source 25 through the way 21 to the reservoir 30. Simultaneously, the pump is coupled by means of way 15 to suction 17. This causes a reduction of pressure in the pump allowing the ventricle-simulating means to expand. This is the situation which is contemplated upon power failure, i.e., absence of any actuation of the valve 11, and thus absence of means whereby pressure fluid from the pressure input 25 can expand the ventricle beyond its failure limit. The spool is urged into the position shown in FIG. l'by the spring provided as part of the valve.

During normal operation, however, the spool 14 is moved to the alternate position so that the reservoir 30 is coupled to the pump 10 'by means of the dotted line way 33. In this position of the spool 14 both the pressure fluid source 25 and the suction source 17 are disconnected from the pneumatic circuit.

The adjustable constriction 28 provides a means for varying the pressure in the conduit 14 and therefore contributes to the determination of the volume delivered to the pump 10by virtue of the extent to which the piston 32 is moved in the cylinder 31.

The means for reversing or cycling the valve 11 Will now be described in conjunction with FIG. 2. In FIG. 2 the central upper portion of the diagram represents an output circuit wherein the symbol Z represents a solenoid position shown (comconduit 18. Suitably a bottom left hand and central portion,

. ponents R 11, 12, 13,

coil operatively associated with the valve spool 14. When the solenoid is energized it moves the spool against the bias of the spring into the alternate position. In the illustration given, the solenoid coil or winding Z is rated at 20 ohms andrequires a minimum DC current of 600 milliamperes for switching.

Referring now to the extreme upper left hand corner of FIG. 2, the components F, S, X, D D and R comprise a power supply of rectified (but not filtered) 60 c.p.s. current (13.4 v. RMS). The diode D prevents damaging transient voltage when the solenoid current is operated.

The push-button switch S permits arbitrary manual operation of the valve solenoid, which is otherwise excited by the power-gating action of the PNP and NPN transistors T and T whenever the junction of resistors R and R is raised above its ground reference by a 6-volt step signal.

Such a signal is supplied on a repetitive basis by the remainder of the circuit if switch S is closed.

The components R R C and D supply an 8-volt filtered-and-zener-stabilized, voltage to a unijunction relaxation oscillator and a monostable vibrator (see the respectively, of FIG. 2). By means of the components R R R R and C the unijunction T 3 delivers 1.0 msec., negative 7- volt pulses (at a repetition rate determined by the setting of the potentiometer R through C to the monostable multivibrator. The latter circuit, consisting of the com- R14, 13, CR 4, and 5, deliver-s to the R -R junction through C a corresponding train of rectangular pulses, each having an amplitude of about 7 volts and a width determined by the setting of the potentiometer R The remaining components R R R R and C allow the percent dutycycle of the pulse train to be displayed on the meter M. The circuit design is such that the range of the adjustable pulse repetition rate is 60-180 beats/minute and the duty cycle range is 0-50 percent.

As a further explanation of the above description of practicing the invention, Table 1 below sets forth a description of the circuit components.

Table 1 F-Fuse, 1.0 a., 150 v. S1-Switch, 1.0 a., 150 v. S2-Switch, 1.0 a., 150 v., push button S3-Switch, 1.0 a., 150 v. X-Transformer, Pri. 115 v.60 c.p.s.,

Sec. 26.8 VCT l.0 a., (Triad F-40X) Z--Solenoid, 12 v. DC, 20 ohm (Modernair BV40602B) M-Meter, DC 0-50 ma., Triplett, Model 221PL D1-Diode, 750 ma., 30 v. (TI-1N2069) D2Diode, 750 ma., 30 v. (TI-1N2069) details herein given may R6Resistor, 47K, 0.25 w. R7-Potentiometer, 250K, carbon R8Resistor, ohm, 0.25 w. R9-Resistor, 1K, 0.25 w. RIO-Resistor, 10K, 0.25 w. R11--Resistor, 1K, 0.25 w. R12-Resistor, 2.5K, 0.25 W. R13-Potentiometer, 25K, carbon R14-Resist0r, 1K, 0.25 w. R15-Resistor, 10K, 0.25 w. R16-Resistor, 68K, 0.25 w. R17Potentiometer, 25K, carbon R18-Resistor, 4.7K, 0.25 w. R19Potentiometer, 500 ohm, carbon T1Transistor, power, PNP, 3 a., 30 v., (Motorola 2N2138) T2Transistor, NPN silicon, 20 ma., 30 v., (TI-2N338) T 3Unijunction, 450 mW., (GE-2Nl67 1A) T4Transistor, NPN, silicon, 20 ma., 30 v., (TI-2N338) T5-Transistor, NPN, silicon, 20 ma., 30 v., '(TI-2N338) While in the foregoing specification, a detailed description of an embodiment of the invention has been set down for the purpose of illustration, many variations in the be made by those skilled in the art without departing from the spirit of scope of the invention.

I claim: I

1. Artificial heart energy-supply apparatus comprising an artificial heart, a multi-port valve equipped with a spool arranged for movement between two positions, the artificial heart connected to one of said ports, an expansible reservoir connected to another of said ports, two other ports being coupled to sources of compressible pressure fluid and suction, respectively, said spool in one position coupling said compressible fluid pressure source artificial heart with said reservoir while blocking fluid pressure flow relative to said sources, and electromechanical means tor positioning said spool, said positioning means in the absence of energization thereof being arranged to maintain said spool in said one position.

2. The structure of claim 1 in which a conduit is provided to couple said fluid pressure source with said valve, and means including a restriction 'in said conduit for varying the volume of pressure fluid delivered to said pump from said reservoir.

3. The structure of claim 1 in which said positioning means includes a solenoid for moving said spool, and means including pulse frequency and pulse width variation means coupled to said solenoid for varying the fre-- cluding a unijunction relaxation oscillator and monostable,

multi-vibrator for energizing said solenoid.

References Cited UNITED STATES PATENTS 2,625,933 l/ 1953 Salisbury 128-214 3,037,504 6/ 1962 Everett 23-258.5 3,182,335 5/1965 Bolie 3,-l

RICHARD A. GAUDET, Primary Examiner. D. L. TRULUCK, Examiner. 

1. ARTIFICAL HEART ENERGY-SUPPLY APPARATUS COMPRISING AN ARTIFICAL HEART, A MULTI-PORT VALVE EQUIPPED WITH A SPOOL ARRANGED FOR MOVEMENT BETWEEN TWO POSITIONS, THE ARTIFICAL HEAT CONNECTED TO ONE OF SAID PORTS, AN EXPANSIBLE RESERVOIR CONNECTED TO ANOTHER OF SAID PORTS, TWO OTHER PORTS BEING COUPLED TO SOURCES OF COMPRESSIBLE PRESSURE FLUID AND SUCTION, RESPECTIVELY, SAID SPOOL IN ONE POSITION COUPLING SAID COMPRESSIBLE FLUID PRESSURE SOURCE WITH SAID RESERVOIR AND SAID ARTIFICIAL HEART WITH SAID SUCTION SOURCE, THE OTHER POSITION OF SAID SPOOL COUPLING SAID ARTIFICAL HEART WITH SAID RESERVOIR WHILE BLOCKING FLUID PRESSURE FLOW RELATIVE TO SAID SOURCES, AND ELECTROMECHANICAL MEANS FOR POSITIONING SAID SPOOL, SAID POSITIONING MEANS IN THE ABSENCE OF ENERGIZATION THEREOF BEING ARRANGED TO MAINTAIN SAID SPOOL IN SAID ONE POSITION. 